Diaphragm actuated pulse pump



Feb. 24, 1%70 s. FINDLAY 3,496,874

I DIAPHRAGM ACTUATED PULSE mar I Filed April 16, 1968 2 Sheets-Sheet 1INVE/V7'O2 Magma 1 W J abw 2 I 5y 47-70225?! F 24, 1970 J. S. FINDLAYDIAPHRAGM ACTUATED PULSE PUMP Filed April 16, 1968 United States PatentU.S. Cl. 10338 9 Claims ABSTRACT OF THE DISCLOSURE A pulse pumpconstruction for blood and the like in which a piston and cylinderdevice operates through a flexible diaphragm to create pressurevariations in a pumping chamber. The diaphragm is cup-shaped with itsconcave side facing the pump chamber to reduce pockets which might trapblood. Means are provided for varying the stroke of the piston from amaximum displacement to and including zero displacement while theeffectiveness of the pumping action is maintained as the amplitude ofthe stroke is varied. Means are provided for adjusting the ratio of thestroke of the piston in one direction versus the stroke of the piston inthe opposite direction to adjust the contraction-expansion ratio of thediaphragm. A housing for the pump has a removable base member with aportion of the pump chamber formed in the base member and with thediaphragm being held in position by the base member. An inlet and anoutlet to and from the pump chamber are disposed in the removable basemember, and the base member is symmetrical in design to permit mountingon the housing in opposite orientations to reverse the flow of bloodthrough the pump chamber SUMMARY OF THE INVENTION This invention relatesto a pulse pump for blood and is intended as a supplement to or asubstitute for the heart in circulating blood. In order to fulfill thisfunction, certain features are important as set forth below.

The principal object of this invention is to provide a new and improvedpulse pump for circulating blood and the like.

The pulse pump of this invention includes a piston which reciprocates ina cylinder formed in a housing above a pump chamber. A cup-shapeddiaphragm extends across the center of the chamber and is caused to flexupwardly and downwardly in accordance with movement of the piston. Checkvalves are positioned at an inlet and an outlet to the pump chamber tocontrol in-flow and outflow of the blood. The piston is reciprocated bya motor driven crank, and the motor is of variable speed to vary thepumping rate. The piston is pivotally secured to the free end of thecrank and the pivot point or fulcrum of the crank is adjustable so thatthe length of stroke of the piston may be varied.

An important feature of the pulse pump set forth in the precedingparagraph is that the fulcrum may be moved all the way to the end of thecrank so that a condition of zero piston displacement is achieved topermit transferring the pumping operation from one pump to another.

Another feature of this invention is that the ratio of the stroke of thepiston in one direction versus the stroke of the piston in the oppositedirection is adjustable to adjust the contraction-expansion ratio of thediaphragm which simulates the systolic and diastolic cycle of a heart.

A further feature of this invention is that the center of the pistonstroke moves toward the diaphragm as the amplitude of the stroke isincreased.

3,496,874 Patented Feb. 24, 1970 Still another feature of this inventionis that each of the check valves which control the in-flow and theoutflow of the blood at the pump chamber is comprised of a conical,three leaved flexible member, the walls of the leaves being tapered fromthe base toward the apex of the cone so that the valve opens and closeseasily without damage to the blood even with small flow rates.

Yet a further feature of this invention is that the diaphragm iscup-shaped with the concave surface of the diaphragm facing toward thepump chamber to reduce pockets which might trap blood and where theblood might clot.

Further features, objects, and advantages of the invention will be setforth in the following detailed description taken in connection with theaccompanying drawings.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevational view of apulse pump embodying the invention, with the housing for the pumpchamber in section;

FIG. 2 is a cut-away section taken generally along the line 22 of FIG.1;

FIG. 3 is a partial elevational view of the concentric drive means ofFIG. 1, with the pivot for the crank arm adjusted to shorten the pistonstroke;

FIG. 4 is a view similar to that of FIG. 3, with the drive meansadjusted to zero piston displacement;

FIG. 5 is a section taken generally along the line 55 of FIG. 4;

FIG. 6 is a section taken generally along the line 6-6 of FIG. 3; and

FIG. 7 is an elevational View showing a modified form of means foradjusting the piston stroke.

DETAILED DESCRIPTION OF THE INVENTION Referrng to the drawings, thedevice of this invention is shown as comprising a pulse pump which isintended as a substitute for a heart in circulating blood. The deviceincludes a framework generally designated 10 on which the pump chamber,drive means and control elements of this invention are mounted. Theframework 10 includes upper support braces 11, lower support braces 12,and vertical supporting legs 13. The pulse pump is operated by a motor Mwhich has a variable speed which may be controlled to vary the pumpingrate.

A housing block 14 (FIG. 1), having a lower removable base portion 14A,is mounted by bolts 16 to the horizontal support brace 12. The housingblock 14 and base portion 14A have facing recesses which combine to forma pumping chamber 18 which has inlet and outlet passages 20 and 22,respectively. Appropriate check valve assemblies, generally designated24, are disposed in the inlet and outlet passages to control the inflowand out-flow of the blood. These check valves 24 are shown in detail inFIG 2 and will be described in greater detail hereinafter. At thispoint, it should be pointed out that the removable base portion 14A ofthe housing block 14 is symmetrical and secured to the housing block bya plurality of bolts 26 symmetrically arranged so that the base portioncan be mounted on the housing in opposite orientations to reverse theflow of blood in relation to the portion of the pump chamber 18 formedby the upper housing block 14.

A piston 28 is reciprocated by the motor M in a cylinder 30 formed inthe housing block 14 above the pump chamber 18. The housing block 14 hasan annular extension 32 extending through an opening 34 in thehorizontal support brace 12 to form an upward extension of the cylinder30. The piston 28 is mounted on the lower end of a piston rod 36. Acup-shaped flexible diaphragm 38 of rubber or like material extendsacross the pump chamber 18 and creates pressure variations in the pumpchamber in response to reciprocation of the piston 28 to draw the bloodin through the inlet passage 20 and force the blood out through theoutlet passage 22. The diaphragm has a peripheral lip 38A which isclamped between annular complementary recesses formed in the housingblock 14 and base portion 14A. The concave surface of the diaphragm 38faces the pump chamber to reduce pockets which might trap blood andwhere the blood might clot. The diaphragm 38 is easily removed forcleaning or replacement by simply removing the housing base portion 14A.

The check valve assemblies 24 which control the flow of blood throughthe pump chamber 18 are shown in detail in FIG. 2 and each assemblyincludes a soft flexible valve member 40 which is made of rubber or likematerial. The valve members 40 are conically shaped and are slit toprovide a three-leaf configuration. The walls of the leaves are taperedfrom the base toward the apex of the cone so that the valve opens andcloses easily, without damage to the blood, even with small flow rates.As with the diaphragm 38', these valve members are designed to minimizeareas where blood flow can stagnate and clot. The valve members 40include marginal lips 40A which are clamped in annular recesses in thehousing base portion 14A by abutment members 42, each of which has anannular shoulder 42A engaging the lip 40A of the valve member 40. Eachof the abutment members 42 has a nipple portion 42B for receivingappropriate tubing. The abutment members are held in place by sleevemembers 44 "which engage the shoulders 42A and which are threaded intoappropriate bores in the housing base portion 14A.

The piston 28 and piston rod 36 are reciprocated by the motor M througha crank or rocker arm 46 which is concentrically fixed pivotally to adisc-shaped rotating member 48 operated by the motor M. The upper end ofthe piston rod 36 is pivotally secured to the free end of the crank 46,as illustrated best in FIGS. 1 and 5. The crank 46 is pivoted on a pivotbracket 50 which forms a fulcrum for the crank.

The fulcrum 50 is movably adjustable in a direction normal to the pistonrod 36 to vary the stroke of the piston 28 and thus the volume of bloodpumped on each stroke of the piston. This is accomplished by providinggrooves 52 extending longitudinally along the crank 46 and pins 54 whichare fixed to the base of the pivot bracket 50 and which extend into thegrooves 52 in a manner best illustrated in FIG. 5. A worm gear 56 (FIG.6), which is rotated by a control knob 58 on the front of the frame 10,moves the pivot bracket 50 normal to the piston rod 32 to move the pins54 in the grooves 52 longitudinally of the crank arm 46. The worm gear56 is threaded into a shaft member 60 (FIGS. and 6) extending upwardlyfrom the pivot bracket 50. As the control knob 58 is turned to rotatethe worm gear 56, the shaft '60 and the pivot bracket 50 are movedlinearly along the worm gear in a direction normal to the piston rod 36.The pivot bracket 50 moves in a bracket housing 62 and when the bracketis moved to a position corresponding to the desired piston displacement,a tightening knob '64 which is threaded on the upper end of shaft 60 maybe utilized to hold the pivot bracket in place. It can be seen that asthe pivot bracket 50, which forms the fulcrum for the crank 46, moves tothe right as viewed in FIG. 1 to a position closer to the piston rod 36,the lever arm formed by the crank on the right of the pivot bracket 50is shortened and consequently the stroke of the piston is shortened.This can be seen by comparing the position of the pivot bracket 50 shownin FIG. 1 with that shown in FIG. 3. In FIG. 3, the pivot bracket 50 iscloser to the piston rod 36 and thus results in a shorter piston stroke.

Referring to FIG. 4, an important feature of the blood pump of thisinvention is that the fulcrum formed by the pivot bracket 50 may bemoved all the way to a position where the pins '52 on the pivot bracket50* are disposed in the slots 52 in vertical alignment with the pistonrod 36 so that a condition of zero piston displacement is achieved whilestill maintaining the piston rod operatively connected to the motor M.The reduction of the piston stroke to zero permits the transfer of thepumping operation from one pump to another. It should also be pointedout that as the stroke of the piston increases, the center of the pistonstroke moves toward the diaphragm reducing the volume of air between thediaphragm and the piston. There is suflicient leakage around the pistonso that the volume of air between the piston and diaphragm adjustsautomatically.

Another feature of the pulse pump of this invention is that means areprovided for adjusting the ratio of the piston stroke in one directionversus the piston stroke in the opposite direction to thereby adjust thecontractionexpansion ratio of the diaphragm 38- which corresponds to thesystolic and diastolic cycle of a heart. This is accomplished bymounting the motor M on the horizontal supporting brace 10 by aplurality of bolts 70 (FIG. 1) which extend through longitudinal slots72 in the brace 12. The position of the motor with respect to the pivotbracket 50 can be varied by loosening the bolts 70 and moving the motoralong the brace 12. The left-hand end of the crank 46 has a slot 74which receives a pin 76 to accommodate the movement of the motor. Inorder to comprehend how the movement of the motor adjusts the strokeratio of the piston, it would be helpful to visualize imaginary linesdrawn from the pivot point (of pivot bracket 50) tangentially toopposite sides of the rotating disc 48. It can be seen that the closerthe motor M is to the pivot bracket 50 the shorter would be the are onthe periphery of the disc between the points where these two imaginarylines would meet the disc. This are would correspond to one stroke ofthe piston while the are about the remainder of the disc wouldcorrespond to the opposite stroke of the piston. Vice versa, as themotor is moved to the left in FIG. 1 away from the pivot bracket 50 theratio of the strokes of the piston would more closely approach a 5050ratio.

Referring to FIG. 7, it can be seen that by inclining the worm gear 56in the manner shown, the pivot bracket '50 is lowered toward thediaphragm as the length of the piston stroke is shortened. Thus, withthis arrangement, the center of the piston stroke will move towards thediaphragm as the amplitude of the stroke is decreased. This is desirableso that the air space between the diaphragm and the piston does not dampthe diaphragm action with extremely short piston strokes.

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations should be understoodtherefromas some modifications will be obvious to those skilled in theart.

I claim:

1. A pulse pump, including a housing having a pump chamber and acylinder therein, a flexible diaphragm between the chamber and one endof said cylinder, a piston mounted on a piston rod for reciprocatingmovement in opposite directions in said cylinder to expand and contractsaid diaphragm, drive means operatively connected to said piston rod forreciprocating the piston within the cylinder, the improvement comprisingmeans for adjusting the stroke of said piston between a predeterminedmaximum displacement to and including zero displacement whilemaintaining the drive means operatively connected to the piston.

2. The pulse pump of claim 1 wherein said adjusting means effects achange in the center of the piston stroke as the displacement of thepiston increases.

3. The pulse pump of claim 1 wherein said adjusting means changes thecenter of the piston stroke toward said one end of the cylinder as thedisplacement of the piston decreases to prevent the air in the spacebetween,

the piston and the diaphragm from damping the diaphragm action forpiston strokes of small amplitude.

4. The pulse pump of claim 1 wherein said drive means includes arotating member, and including a concentric link means comprising acrank arm pivotally connected at one end to said rotating member and atthe other end to said piston rod, a pivot bracket pivotally secured tosaid crank arm intermediate the ends of the crank arm so that rotationof said member oscillates the other end of the crank arm to reciprocatethe piston in response to rotation of said member, and means foradjusting said pivot bracket along said crank arm to and including apoint in alignment with the axis of said piston rod to effect zeropiston displacement.

5. The pulse pump of claim 1 including means for adjusting the ratio ofthe stroke of said piston in one direction versus the stroke of thepiston in the opposite direction to thereby adjust thecontraction-expansion ratio of said diaphragm.

6. The pulse pump of claim 5 wherein said drive means includes arotating member, and including a concentric link means comprising acrank arm pivotally connected at one end to said rotating member and atthe other end to said piston rod, a pivot bracket secured to said crankarm intermediate the ends of the crank arm so that rotation of saidmember oscillates said other end of the crank arm, said one end of thecrank arm having a slot for receiving a pin on said rotating member, andmeans for moving said rotating member toward and away from said pivotbracket.

7. In a pulse pump for blood and the like including a housing having apump chamber with an inlet and an outlet for the passage of bloodthrough the chamber and having a removable base member with a portion ofsaid pump chamber formed therein, check valve means for directing theflow of blood through said inlet into said chamber and out of saidchamber through said outlet, and means in communication with said pumpchamber for creating pressure variations in the chamber to draw theblood in through said inlet and force the blood out through said outlet,the improvement in which said inlet and said outlet are disposed in saidbase member, said base member being symmetrical and mountable on saidhousing in opposite orientations to reverse the flow of liquid throughsaid chamber.

8. A pulse pump comprising a housing having a pump chamber; a pair ofpassages extending through the wall of the housing for flow of liquidthrough the chamber, each of said passages having an inner portion of afirst diameter adjacent said chamber and an outer portion of a largerdiameter with a shoulder joining the two portions; 2. check valve ineach of said passages to direct the flow of liquid into said chamberthrough one passage and out of said chamber through the other, the checkvalve having a flexible one-way valve portion, and an outwardly directedmarginal lip extending circumferentially therearound, said marginal lipbeing engageable with the shoulder at the inner end of each passage forflow of liquid through said chamber in either direction; abutment meansto clamp said check valves in each passage, and having a portion forconnection to each of said passages; and means connected with said pumpchamber for creating pressure variations in the chamber to draw liquidin through the selected input and force liquid out through the selectedoutput.

9. A pulse pump construction, comprising a housing having a pumpchamber, an inlet and an outlet for the passage of liquid through thechamber, check valve means associated with each of said inlet and saidoutlet to direct the flow of liquid through said inlet into said chamberand out of said chamber through said outlet, and means in communicationwith said pump chamber for creating pressure variations in the chamberto draw liquid in through the inlet and force liquid out through theoutlet, in which said means for creating pressure variations includes aflexible diaphragm forming a sealed closure between said last namedmeans and said pump chamber, said diaphragm being cup-shaped with itsconcave side facing the pump chamber to reduce pockets which might trapblood and where the blood might clot, the improvement in which thedirection of flow of liquid through said chamber is parallel to a planeformed by the marginal edge of said cup-shaped diaphragm.

References Cited UNITED STATES PATENTS 2,548,807 4/1951 Morgan et al103-38 X 2,764,097 9/ 1956 Browne.

2,960,936 11/1960 Dean et a1. 10338 3,127,846 4/1964 Kerns 1031523,218,979 11/1965 Baldwin 103-38 X 3,327,322 6/1967 Norton 103-38LEONARD H. GERIN, Primary Examiner US. Cl. X.R.

